<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>05_面试题</title>
</head>
<body>
<script type="text/javascript">
  /*
  测试题1: 先预处理变量, 后预处理函数
  */
  function a() {}
  var a;
  console.log(typeof a)


  /*
  测试题2: 变量预处理, in操作符
   */
  if (!(b in window)) {
    var b = 1;
  }
  console.log(b)

  /*
  测试题3: 预处理, 顺序执行
   */
  var c = 1
  function c(c) {
    console.log(c)
    var c = 3
  }
  c(2)

</script>
</body>
</html>